Optimized triangulation algorithm. Must more faster now.

Added loader for TERRAGEN terrains (*.ter).
ScenePreprocessor generates a default material if none is given.
AC: file extension bug
Added terragen test files.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@279 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

code/ValidateDataStructure.cpp

@@ -291,6 +291,8 @@ void ValidateDSProcess::Execute( aiScene* pScene)
 	}
 	else if (!(mScene->mFlags & AI_SCENE_FLAGS_INCOMPLETE))
 	{
+		// NOTE: ScenePreprocessor generates a default material if none is there
+		// (and at least one mesh is found). So this should never be triggered ...
 		ReportError("aiScene::mNumMaterials is 0. At least one material must be there");
 	}
 	else if (pScene->mMaterials)